With a healthy and productive Devonte Fields this fall, TCU's defensive line could be an elite unit. Jerome Miron/USA TODAY Sports

1. TCU (pre-spring ranking: 2): Devonte Fields appears to be back, which is a scary proposition for the rest of the Big 12. The 2012 Big 12 AP Defensive Player of the Year basically had a fruitless sophomore campaign, which ended with season-ending foot surgery. But this spring, defensive coordinator Dick Bumpas noted that Fields was making the plays he did as a freshman All-American. Even without Fields, this would be a good D-line, headlined by veteran tackles Chucky Hunter and Davion Pierson. But with Fields playing up to his potential, this line could be elite.

2. Oklahoma (1): Not only did the Sooners return the entire line that destroyed Alabama in the Allstate Sugar Bowl, they’ve added three redshirt freshmen who are clamoring for playing time. Charles Walker is the most athletic tackle on the roster, and he ran the fastest tackle 40 time (4.67 seconds) of the Bob Stoops era. Tackle Matt Romar quietly emerged this spring and could be on the verge of taking away snaps from some of the veterans inside. Ogbonnia Okoronkwo showed this spring he's yet another Sooner capable of getting to the quarterback off the edge. There's a debate on the best D-line in the league. There’s no debate on the deepest, with Oklahoma capable of going three-deep across the board.

3. Baylor (6): Coach Art Briles believes he has one of the best defensive lines in the country, and there's reason to believe he might be right. The Bears made the biggest jump on this list, thanks to the development of end Shawn Oakman and emergence of tackle Javonte Magee. Briles called the 6-foot-9 Oakman “unblockable” during the spring. Oakman already flashed plenty of potential last season as a sophomore, finishing sixth in the league with 12.5 tackles for loss. Magee, who might be the most highly-touted high school defender Briles has ever signed, sat out his freshman season while dealing with a personal issue. But he established himself this spring and could beat out returning starter Beau Blackshear. With former four-star signee Andrew Billings (who played as a true freshman) also poised for a big year at the other tackle spot, Briles could indeed be proven correct in the fall.

4. Texas (3): The Longhorns boast two of the league’s blue-chip defensive linemen in end Cedric Reed and tackle Malcom Brown. But whether this unit rises to the top of the league will hinge on the supporting cast. If athletic end Shiro Davis and run-stuffing tackle Desmond Jackson play up to their potential, and the Longhorns can get a boost from incoming freshmen Derick Roberson and Poona Ford, this could be a foundational positional unit in Charlie Strong’s first season.

5. Kansas State (4): Like Texas, the Wildcats have two blue-chip pieces returning up front in All-Big 12 end Ryan Mueller and tackle Travis Britz. They’re banking they’ll soon be adding a third in Terrell Clinkscales, who will be arriving to Manhattan shortly. Clinkscales, whom the Wildcats snatched away from Nebraska, was the nation’s No. 4-rated juco DT, and at 315 pounds, could be the run-stuffer K-State currently lacks.

6. Oklahoma State (5): With so much turnover elsewhere, the Cowboys will be counting on their line to be their anchor defensively.There’s reason to believe it could be that and more. Sam Wren received votes for Big 12 Defensive Newcomer of the Year last season, while Emmanuel Ogbah garnered consideration for Big 12 Defensive Freshman of the Year. Throw in promising redshirt freshmen Vili Leveni, Ben Hughes and Vincent Taylor, who all showed signs this spring they might be ready to contribute, along with veterans James Castleman, Ofa Hautau and Jimmy Bean, and Oklahoma State could have the anchor up front it needs while the rest of the defense retools.

7. West Virginia (7): This will probably be the weakest area of West Virginia defense, but with their talent at linebacker, the Mountaineers don’t have to be great up front. Dontrill Hyman, Christian Brown and Kyle Rose are currently the starters coming out of the spring. But the player to watch up front is sophomore Darrien Howard, who rapidly progressed since having his redshirt pulled late in 2013. If Howard develops into an impact player, he could give the Mountaineers a huge jolt up front.

8. Texas Tech (9): The Red Raiders tried to get by this spring while awaiting the horde of defensive line help set to arrive this summer. All told, the Red Raiders signed four juco D-linemen, only one of which – Keland McElrath -- enrolled early (McElrath was hobbled by a stress fracture all spring to boot). To be better up front, Tech, which ranked ninth in run defense last fall, will need at least a couple of its juco transfers to hit.

9. Kansas (10): Keon Stowers quietly has become as one of the better tackles in the league. He was the defensive MVP of Kansas' spring game after collecting eight tackles from his defensive tackle spot, and he was voted captain for a second straight year. Stowers and linebacker Ben Heeney will lead a defense that returns nine starters and could surprise after gaining confidence from playing Oklahoma and Texas tough last season.

10: Iowa State (8): The Cyclones took it on the chin this spring, with projected D-line starters Rodney Coe and David Irving both getting kicked off the team. Iowa State got a boost shortly after spring ball ended when 2013 starting tackle Brandon Jensen changed his mind about leaving the team. The Cyclones should be solid at end with Cory Morrissey and Mitchell Meyers, but even with Jensen’s return, interior line depth is a major concern.